The ongoing technological development in the field of semiconductor fabrication is resulting in integrated circuits with higher device density, lower power consumption, and higher operation speed. Generally, a highly integrated circuit is designed using a multi-layer wiring structure that includes an embedded metal wiring layer and a contact plug.
In addition, an embedded metal wiring layer and a contact plug are formed by forming a contact hole in an insulating film and filling the contact hole with a conductive material.
As the thickness of an insulating film in which a contact hole is formed increases, it becomes difficult to secure the contact area and to completely fill the contact hole to a bottom surface thereof with a conductive material, thereby causing open defects.